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PubMed2001

Long term results of cardioverter-defibrillator implantation in patients with right ventricular dysplasia and malignant ventricular tachyarrhythmias.

OBJECTIVE: To study the outcome of patients with arrhythmogenic right ventricular dysplasia treated with an implantable cardioverter-defibrillator (ICD) for ventricular tachyarrhythmias complicated by haemodynamic collapse. DESIGN: Observational study. SETTING: University hospital. PATIENTS: Nine consecutive patients (eight male, one female; mean (SD) age, 36 (18) years) with arrhythmogenic right ventricular dysplasia presenting with ventricular tachycardia and haemodynamic collapse (n = 6) or ventricular fibrillation (n = 3), treated with an ICD. MAIN OUTCOME MEASURES: Survival; numbers of and reasons for appropriate and inappropriate ICD interventions. RESULTS: After a mean (SD) follow up of 32 (24) months, all patients were alive. Six patients received a median of 19 (range 2-306) appropriate ICD interventions for events detected in the ventricular tachycardia window; four received a median of 2 (range 1-19) appropriate ICD interventions for events detected in the ventricular fibrillation window. Inappropriate interventions were seen for sinus tachycardia (18 episodes in three patients), atrial fibrillation (three episodes in one patient), and for non-sustained polymorphic ventricular tachycardia (one episode in one patient). CONCLUSIONS: Patients with arrhythmogenic right ventricular dysplasia and malignant ventricular arrhythmias have a high recurrence rate requiring appropriate ICD interventions, but they also often have inappropriate interventions. Programming the device is difficult because this population develops supraventricular and ventricular tachyarrhythmias with similar rates.

Adult↗

PubMed1994

[The surgical treatment of sustained ventricular tachycardias. The short- and midterm results in the era of the implantable defibrillator and the heart transplant].

BACKGROUND: The surgical treatment of refractory ventricular tachycardia has been shown to be effective. Its use has been limited by a high perioperative mortality. OBJECTIVE: To study the extent to which the introduction of new therapeutic options, i.e. the implantable defibrillator and cardiac transplantation, improves patient selection and results of direct antiarrhythmic surgery. PATIENTS AND METHODS: We analyzed 24 consecutive patients operated upon for ventricular tachycardia (study population). At the same time, 42 patients were treated with implantable defibrillator and 11 patients, with symptomatic ventricular arrhythmias, underwent cardiac transplantation (reference population). RESULTS: The clinical characteristics of the study population (age, functional class, ejection fraction) were significantly different from those of both reference groups. Nine patients (38%) were operated upon because of electrical instability and/or contraindication for other therapeutic options despite of having criteria of high surgical risk. There was one perioperative death (4.2%) and no other early arrhythmic recurrences. Persistence of inducibility occurred in 5 cases (22%). During follow up (35 +/- 22 months) there was a single arrhythmic recurrence. Three patients died of nonarrhythmic causes. Presently, 16 patients are in I or II NYHA functional class. CONCLUSIONS: 1) Direct surgery remains as a useful tool in the treatment of ventricular tachycardia; 2) clinical differences among groups caused by the individual selection of the three therapeutic options preclude comparison of their results, and 3) the introduction of other therapeutic approaches, although resulting in only partial improvement of patient selection, leads to acceptable short and mid-term results of direct antiarrhythmic surgery.

Adult↗

PubMed1997

The AVID trial: evidence based or randomized control trials--is the AVID study too late? Antiarrhythmics Versus Implantable Defibrillators.

A great body of clinical evidence has been accumulated--before and without the AVID trial--showing that implantable defibrillators prolong life better than currently available antiarrhythmic drugs. With this evidence already available, we question the validity of a trial that attempted, in effect, to place a price tag on life and quality of life.

Anti-Arrhythmia Agents↗

PubMed1993

Visualization of implantable defibrillator patches by two-dimensional echocardiography.

Implantable cardioverter defibrillators are being used with increasing frequency for the management of life-threatening ventricular arrhythmias. In order to determine whether the titanium mesh of the defibrillator patch causes ultrasonographic acoustical interference, 30 patients underwent prospective serial echocardiographic examination. In addition, studies were reviewed to determine whether the defibrillator patches could be visualized with standard two-dimensional echocardiography. In no patient did the anterior patch produce acoustical interference, and, unless specific measures were utilized (such as a standoff pad, a zoom feature, or a 5-MHz transducer), the patches were rarely visualized.

Adult↗

PubMed1999

Interactions of antiarrhythmic drugs with implantable defibrillator therapy for atrial and ventricular tachyarrhythmias.

Implantable cardioverter defibrillators (ICDs) have proven highly successful in the treatment of recurrent ventricular and atrial arrhythmias. Despite their high efficacy in terminating arrhythmias, concomitant therapy with antiarrhythmic drugs in ICD recipients remains common. Antiarrhythmic drugs are employed in an attempt to to limit patient exposure to high-energy shocks, primarily by reducing the number of arrhythmia reccurrences, suppressing coexisting arrhythmias, affecting rate and organization of tachycardias, and increasing efficacy of painless pacing therapies. Data regarding interaction of antiarrhythmic drugs with ICDs are incomplete and mostly based on animal models; however, it is clear that antiarrhythmic drugs affect all aspects of function of devices such as defibrillation threshold, pacing threshold, and sensing of both atrial and and ventricular arrhythmias. Because significant change in any of these functions may result in a nonfunctional device, and magnitude of drug effect in an individual patient is unpredictable, careful assessment of ICD function after an institution of therapy with antiarrhythmic drugs is mandatory.

Anti-Arrhythmia Agents↗

PubMed2003

Is inappropriate implantable defibrillator shock therapy predictable?

OBJECTIVE: To identify implantable cardioverter defibrillator (ICD) patients who are at risk of receiving inappropriate shock. BACKGROUND: Inappropriate ICD shock, usually from atrial fibrillation (AF) or sinus tachycardia (ST), is a common problem. We hypothesized that clinical variables would predict which patients with single chamber ICDs would be more likely to receive inappropriate therapy and be candidates for more accurate discriminators such as those available in dual chamber ICDs. METHODS: The ICD registry at St. Michael's Hospital has it's clinical information and demographic data updated after each clinic visit. Inappropriate shock was considered as the outcome variable. Possible predictors considered were age, gender, ejection fraction, NYHA class, prior CABG and prior history of AF. Univariate predictors were identified using t-test for continuous variables and Chi-square test for categorical variables. Multivariate predictors were identified using stepwise logistic regression analyses. RESULTS: Of 299 patients, 261 had complete data for analysis. In this population 78% were male, mean age was 60 +/- 13 years, mean ejection fraction was 37 +/- 15% and mean follow up was 53 +/- 36 months. One hundred and sixteen of the 261 patients (44%) received one or more inappropriate therapies (73% within 2 years of receiving their device), and 140 (51%) received one or more appropriate therapies. Significant predictors of inappropriate therapy by multivariate model were prior AF (OR 2.6, 95% CI 1.5-4.5) and NYHA class 1 vs. classes 2-4 (OR 2.2, 95% CI 1.2-3.7). CONCLUSION: Clinical characteristics of ICD patients can predict those at risk for inappropriate shock and should be considered for interventions to decrease such shocks.

Aged↗

PubMed1999

Who needs an implantable defibrillator?

Ventricular arrhythmias account for 80% of sudden cardiac deaths. The implantable defibrillator (ICD) is an effective means of preventing these deaths. This article discusses which patients may benefit from ICD implantation and addresses the cost-effectiveness of their use.

Anti-Arrhythmia Agents↗

PubMed2001

"Stable" ventricular tachycardia is not a benign rhythm : insights from the antiarrhythmics versus implantable defibrillators (AVID) registry.

BACKGROUND: Sustained ventricular tachycardia (VT) can be unstable, can be associated with serious symptoms, or can be stable and relatively free of symptoms. Patients with unstable VT are at high risk for sudden death and are best treated with an implantable defibrillator. The prognosis of patients with stable VT is controversial, and it is unknown whether implantable cardioverter-defibrillator therapy is beneficial. METHODS AND RESULTS: Screening for the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial identified patients with both stable and unstable VT. Both groups were included in a registry, and their clinical characteristics and discharge treatments were recorded. Mortality data were obtained through the National Death Index. The mortality in 440 patients with stable VT tended to be greater than that observed in 1029 patients presenting with unstable VT (33.6% versus 27.6% at 3 years; relative risk [RR]=1.22; P:=0.07). After adjustment for baseline and treatment differences, the RR was little changed (RR=1.25, P:=0.06). CONCLUSIONS: Sustained VT without serious symptoms or hemodynamic compromise is associated with a high mortality rate and may be a marker for a substrate capable of producing a more malignant arrhythmia. Implantable cardioverter-defibrillator therapy may be indicated in patients presenting with stable VT.

Aged↗

PubMed1998

Potential impact of antiarrhythmic drugs versus implantable defibrillators on the management of ventricular arrhythmias: the Midlands trial of empirical amiodarone versus electrophysiologically guided intervention and cardioverter implant registry data.

BACKGROUND: Survival was prolonged in selected patients with sustained ventricular arrhythmias who received implantable cardioverter defibrillators (ICDs) in the antiarrhythmics versus implantable defibrillators (AVID) study. The Midlands trial of empirical amiodarone versus electrophysiologically guided intervention and cardioverter implant in ventricular arrhythmias (MAVERIC) registry is a population based trial. OBJECTIVE: To determine the number of patients who satisfy the AVID criteria because of the high cost of ICDs. DESIGN: Observational study, based on a continuing trial. SETTING: All coronary care units in the Midlands region in the United Kingdom (population 9.1 million). PATIENTS: Patients presenting to a coronary care unit with sustained ventricular arrhythmias not related to an acute myocardial infarction are entered onto the registry. Those who consent to the MAVERIC study are randomised to receive either empirical amiodarone or electrophysiologically guided treatment. Demographic data, details of clinical presentation, and echocardiographic findings are collected. These data have been used to calculate the number of patients who satisfy the AVID criteria and would benefit from ICD implantation. The financial implications have been calculated for the region and nationally. RESULTS: 132 patients were entered onto the registry during the first five months of the MAVERIC study; 69 patients fulfilled the AVID criteria. Extrapolation of these data over a 12 month period suggests implantation of at least 166 new ICDs (compared with 23 implants in 1996). This would increase the UK ICD implant rate from five to at least 18 per million of the population, costing the National Health Service 24.1 Pounds million per annum. CONCLUSION: Application of the AVID criteria in the UK will cause a great increase in the ICD implant rate, with serious financial implications.

Aged↗

PubMed1999

Effects of defibrillator implantation testing on myocardial metabolism.

BACKGROUND: The effects of fibrillation/defibrillation episodes (FDEs) during defibrillator implantation on myocardial metabolism were investigated at various defibrillation energies in patients with different cardiac pathologies. METHODS: Myocardial lactate extraction (MLE) was examined during defibrillation threshold (DFT) testing in patients with either coronary artery disease (CAD, n = 20) or non-ischemic cardiomyopathy (CM, n = 10). Defibrillation pulses were released 15 seconds after induced fibrillation. A test cycle of four FDEs separated by 2-minute intervals was applied in each case. RESULTS: Mean MLE decreased significantly from 28 +/- 4% before FDEs to 8 +/- 5% immediately after all episodes in CAD patients, but recovered to 27 +/- 7% within 2 minutes even in patients with reduced left-ventricular function. In patients with CM mean MLE decreased markedly from 29 +/- 3% to -11 +/- 3% immediately after each FDE but increased to baseline (33 +/- 8%) within the recovery period. MLE changes were independent of defibrillation energy in all cases. CONCLUSIONS: Myocardial lactate production, suggesting cardiac ischemia, was observed in patients with CM, but not in patients with CAD. But recovery of myocardial lactate extraction was not faster in CAD patients, indicating that the fixed FDE cycle used was well tolerated by all patients.

Adult↗

PubMed2004

Sudden cardiac death and channelopathies: a review of implantable defibrillator therapy.

This article focuses on implantable cardioverter-defibrillator (ICD) therapy in the child/adolescent who is predisposed to sudden cardiac death because of an underlying channelopathy. As such, the primary channelopathies are reviewed briefly. Next, the history of the ICD device and the technological advancements that have enabled its use in pediatrics are discussed. Finally, the clinical experience with ICDs in the young is summarized and general indications for device therapy in young patients who have a channelopathy are provided.

Adolescent↗

PubMed2005

Coronary risk factors and inflammation in patients with coronary artery disease and internal cardioverter defibrillator implants.

BACKGROUND: The internal cardioverter defibrillator (ICD) is increasingly used to treat ventricular tachyarrhythmias in patients with coronary artery disease (CAD). The burden of coronary risk factors and inflammation is however not well studied in these high risk patients. STUDY AIMS: The aim of the present study was to describe the prevalence of coronary risk factors (including lipid values) and inflammation (including high sensitive-C-reactive protein, hs-CRP) in patients with CAD and ICD implants. METHODS: Baseline clinical characteristics and laboratory results of all eligible patients for the Cholesterol Lowering and Arrhythmias Recurrences after Internal Defibrillator Implantation trial (CLARIDI trial) were used. All patients had documented CAD, an ICD implant and were not yet treated with statins. Coronary risk factors, lipid values, glycated haemoglobin (HbA(1c)) and hs-CRP levels were determined. RESULTS: In the 110 included patients (mean age 68+/-9 years, LVEF 40+/-17%, NYHA class II-III in 47%), a high prevalence of coronary risk factors was documented: current smoking in 18%, body mass index > or =30 kg/m(2) in 16%, blood pressure > or =140/90 mm Hg in 40%, history of diabetes in 12%, and HbA(1c) > or =6% in 16% of patients not known with diabetes. A total cholesterol >175 mg/dl was found in 76% of patients and an LDL cholesterol >100 mg/dl in 83%. Finally, median hs-CRP was 4.8 mg/l (interquartile range 2.5-13.9 mg/l). Hs-CRP values > or =2 mg/l were noted in 83% of all patients and in 68% of patients who had an ICD implant more than 6 months before inclusion. CONCLUSION: In CAD patients with ICD implants, the burden of coronary risk factors is high, often unrecognized and/or under-treated. Persistent inflammation is found in the majority of these patients.

Adult↗

PubMed1997

Automatic arrhythmia identification using analysis of the atrioventricular association. Application to a new generation of implantable defibrillators. Participating Centers of the Automatic Recognition of Arrhythmia Study Group.

BACKGROUND: Atrioventricular association is a key criterion for arrhythmia diagnosis. Its use in a defibrillator should significantly reduce the incidence of inappropriate shocks. Therefore, we evaluated the diagnostic accuracy of an algorithm that uses dual-chamber sensing and analysis of atrioventricular association to discriminate ventricular from supraventricular arrhythmias in a prototype of an implantable defibrillator. METHODS AND RESULTS: The algorithm performed a stepwise analysis of arrhythmias. The rhythm was first classified on the basis of cycle lengths. Each episode was then classified as supraventricular or ventricular in origin on the basis of the stability of cycle lengths and atrioventricular association. This algorithm was evaluated in 156 episodes of induced sustained tachycardias. Eighty-nine tachycardias were taken from the Ann Arbor electrogram library; the others were recorded in 50 patients during electrophysiological studies. The atrial and ventricular signals were stored on an external recorder and then injected into an external prototype of a defibrillator system. The algorithm correctly diagnosed 96% of ventricular tachycardia episodes, 100% of ventricular fibrillation episodes, and 92% of double-tachycardia episodes. The mean detection time for ventricular tachycardia was 2.6 +/- 0.8 seconds, and for ventricular fibrillation, it was 2.1 +/- 0.4 seconds. The positive predictive values for the diagnoses of atrial fibrillation and atrial flutter were 92% and 86%, respectively. For ventricular tachycardia and ventricular fibrillation, the values were 95% and 100%, respectively. CONCLUSIONS: Analysis of atrioventricular association promotes reliable differentiation between ventricular and supraventricular tachycardias and should enhance the diagnostic capabilities of implantable defibrillators.

Algorithms↗

PubMed1994

Experience with two different nonthoracotomy systems for implantable defibrillator in 170 patients.

Implantation of a nonthoracotomy system (Medtronic PCD or CPI Endotak) was attempted in 170 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) not requiring concomitant cardiac surgery. A nonthoracotomy system could be successfully implanted in 95 of the 115 patients with the PCD system and 49 of 55 patients receiving the Endotak lead system. In 26 patients with failed nonthoracotomy system because of defibrillation threshold (DFT) > 25 joules (J), an epicardial system was implanted at the same setting. Patients receiving the two lead systems were comparable with regard to age, sex, and ejection fraction. However, since the PCD system offers tiered therapy multiprogrammable options, all attempts were made to implant this lead system in patients with VT that could be pace terminated. Mean DFT (15 +/- 4.7 vs 17 +/- 4.6 J; P = 0.03) and implant time (2.5 +/- 0.6 vs 3.3 +/- 0.7 hours; P = 0.02) were less with the Endotak lead system. There was no perioperative mortality. During a mean follow-up of 20 +/- 4 months, there were eight instances of lead dislodgment in patients receiving the PCD system. There were four nonsudden cardiac deaths and one sudden death in the Endotak group and three nonsudden deaths in the PCD group. Sudden cardiac death and total survival using the intention-to-treat analysis during this follow-up period were 99% and 95%, respectively. In conclusion, successful implantation, perioperative mortality, and survival rate are comparable with both lead systems; however, incorporating two defibrillating electrodes in one lead minimizes lead dislodgment and reduces implant time.

Anti-Arrhythmia Agents↗

PubMed2004

Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy.

BACKGROUND: Patients with nonischemic dilated cardiomyopathy are at substantial risk for sudden death from cardiac causes. However, the value of prophylactic implantation of an implantable cardioverter-defibrillator (ICD) to prevent sudden death in such patients is unknown. METHODS: We enrolled 458 patients with nonischemic dilated cardiomyopathy, a left ventricular ejection fraction of less than 36 percent, and premature ventricular complexes or nonsustained ventricular tachycardia. A total of 229 patients were randomly assigned to receive standard medical therapy, and 229 to receive standard medical therapy plus a single-chamber ICD. RESULTS: Patients were followed for a mean (+/-SD) of 29.0+/-14.4 months. The mean left ventricular ejection fraction was 21 percent. The vast majority of patients were treated with angiotensin-converting-enzyme (ACE) inhibitors (86 percent) and beta-blockers (85 percent). There were 68 deaths: 28 in the ICD group, as compared with 40 in the standard-therapy group (hazard ratio, 0.65; 95 percent confidence interval, 0.40 to 1.06; P=0.08). The mortality rate at two years was 14.1 percent in the standard-therapy group (annual mortality rate, 7 percent) and 7.9 percent in the ICD group. There were 17 sudden deaths from arrhythmia: 3 in the ICD group, as compared with 14 in the standard-therapy group (hazard ratio, 0.20; 95 percent confidence interval, 0.06 to 0.71; P=0.006). CONCLUSIONS: In patients with severe, nonischemic dilated cardiomyopathy who were treated with ACE inhibitors and beta-blockers, the implantation of a cardioverter-defibrillator significantly reduced the risk of sudden death from arrhythmia and was associated with a nonsignificant reduction in the risk of death from any cause.

Adrenergic beta-Antagonists↗

PubMed1999

[Effect of defibrillation on hemodynamics during cardioverter defibrillator implantation].

This study evaluated the influences of induced ventricular fibrillation and defibrillation on the hemodynamics in patients with malignant ventricular arrhythmias during cardioverter defibrillator implantation. A total of 15 patients were analyzed, divided into 2 groups based on ventricular contractility. Group A included 6 patients with preoperative left ventricular fractional shortening < or = 0.20 and Group B consisted of 9 patients with fractional shortening > 0.20. Mean blood pressure, cardiac output, pulmonary capillary wedge pressure, and left ventricular stroke work index were measured before and after ventricular fibrillation and defibrillation. In addition, end-systolic wall stress and rate-corrected mean velocity of circumferential fiber shortening were obtained from transesophageal echocardiography. In Group B, measured 30 sec after defibrillation, mean blood pressure, cardiac output, and left ventricular stroke work index increased significantly (p < 0.05), whereas only pulmonary capillary wedge pressure indicated a significant increase (p < 0.001) after defibrillation in Group A. Throughout 5 repeated ventricular fibrillations and defibrillations. Group A showed consistently lower postoperative values than preoperative values for mean blood pressure, cardiac output and left ventricular stroke work index. In contrast, in Group B, the postoperative values were constantly higher than preoperative values. Although end-systolic wall stress decreased after defibrillation in both groups, the magnitude of decrease was significantly greater in Group A than in Group B (p < 0.01). While rate-corrected mean velocity of circumferential fiber shortening increased after defibrillation in both groups, the difference of rate-corrected mean velocity of circumferential fiber shortening between Groups A and B was statistically significant at beats one and 2 following defibrillation (p < 0.05) where Group A indicated a more drastic increase than Group B. In both groups, post-defibrillation end-systolic wall stress and rate-corrected mean velocity of circumferential fiber shortening gradually approached the preoperative values as beats proceeded. These results suggest that repeated defibrillations in patients with poor ventricular contractility potentially deteriorates hemodynamics, presumably because the left ventricle is often intolerant to abrupt arterial collapse by ventricular fibrillation and to subsequent rapid preload increase after defibrillation.

Adult↗

PubMed1997

Clinical and socioeconomic profile of patients with malignant ventricular arrhythmias in 1993 to 1995. AVID investigators. Antiarrhythmics Versus Implantable Defibrillator.

This report summarizes the clinical and socioeconomic characteristics of the first 542 patients entered into the Antiarrhythmics Versus Implantable Defibrillator (AVID) trial. AVID is a multicenter trial comparing a strategy of initial implantable cardioverter-defibrillator placement to initial antiarrhythmic drug therapy in preventing death in patients resuscitated from cardiac arrest who were not taking amiodarone and who did not have an implantable cardioverter-defibrillator in place at the time of the index event. These patients were randomly assigned to immediate defibrillator placement or to "best" medical therapy. Clinical and socioeconomic histories were collected by interview using standard terms developed for the study. Patients without (group 1) and with (group 2) a history of prior cardiac arrest were compared. The mean age of the 542 patients was 65 +/- 10 years, most were men, white, had coronary disease, and were highly functional despite the fact that only a minority were employed. Almost all had some form of health insurance. At the time of the index event, few were taking any therapy to prevent cardiac arrest, even in the group of patients with a history of previous cardiac arrest. Thus, the clinical and socioeconomic profile of patients resuscitated from sudden cardiac death entered into the AVID study is generally as expected. There is a striking absence of any attempt at chronic therapy to prevent cardiac arrest in most patients with a prior ventricular tachycardia or ventricular fibrillation.

Aged↗

PubMed2001

[Daily activities and circadian variation of ventricular tachyarrhythmias in patients with implanted defibrillator].

BACKGROUND AND STUDY AIM: Acute cardiovascular events may be triggered by physical and mental stress. Does also the typical circadian variation of arrhythmia recurrence (morning peak of events) in patients with implanted cardioverter-defibrillator correlate with the individual circadian variation of physical and mental daily activities? PATIENTS AND METHODS: In 29 consecutive patients with a minimum of three documented ventricular tachyarrhythmias after defibrillator implantation the circadian variation of habitual daily activities was determined in a standardized interview and compared to the individual circadian variation of arrhythmic events saved in the defibrillator event memory during long-term follow-up. RESULTS: The habitually highest physical and mental activity was determined during the time period with most arrhythmic events in 55 % and 23 % of patients, respectively. A comparison of the level of activity during the time period with the highest event frequency to the mean activity level during the rest of the day (without sleeping time) revealed significantly higher physical activity during the time of day with the highest arrhythmia recurrence. There was a positive correlation between circadian variation of arrhythmic events and the sum of all activities (r = 0.34, p < 0.05) and physical activities alone (r = 0.25, p = 0.056) while a relationship to mental activities alone could not be shown (r = 0.02, p = 0.84) CONCLUSION: The circadian variation of acute cardiovascular events may be discussed as an essential factor influencing the circadian variation of habitual daily activities in patients with cardiac disease.

Activities of Daily Living↗